Automated leveling and depth control system of a work machine and method thereof

ABSTRACT

An agricultural implement includes a transversely extending frame forming a first, a second, and a third frame section. A first actuator is coupled to the first frame section, a second actuator coupled to the second frame section, and a third actuator coupled to the third frame section. Sensors are coupled to each frame section to detect a height of the respective frame section relative to an underlying surface. A control unit is disposed in electrical communication with the sensors and operably controls the actuators to adjust the height of each frame section.

RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 15/171,632, filed Jun. 2, 2016, which is acontinuation-in-part of U.S. patent application Ser. No. 15/058,745,filed Mar. 2, 2016, the disclosures of which are hereby incorporated byreference in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a hydraulic control system, and inparticular to a hydraulic control system of an implement of a workmachine.

BACKGROUND OF THE DISCLOSURE

In the agricultural industry, wide implements such as field cultivatorsand the like include a main frame and adjacent outrigger or wing framesthat are hinged or pivotably coupled thereto. Conventional controlsystems require an operator or user to estimate how level the differentframes are relative to one another, and also whether each individualframe is level from fore-to-aft. Moreover, many of these systems requirehuman intervention to mechanically adjust the frames to achieve a levelposition across the width of the machine and in the fore-to-aftdirection. This, however, can introduce human error and makes itdifficult to achieve precise machine leveling.

In the present disclosure, a control system is described and illustratedfor providing automatic machine leveling across multiple frame sectionsof a work machine and leveling from front to back of each individualframe section.

SUMMARY

In one embodiment of the present disclosure, an agricultural implementincludes a transversely extending frame forming at least a first framesection, a second frame section, and a third frame section, where thefirst frame section is disposed between the second and third framesections; a hitch member configured to couple to a work machine, thehitch member being coupled to at least one of the first, second, andthird frame sections; a first actuator coupled to the first framesection, a second actuator coupled to the second frame section, and athird actuator coupled to the third frame section; a first sensorcoupled to the first frame section, the first sensor configured todetect a first height of the first frame section from an underlyingsurface; a second sensor coupled to the second frame section, the secondsensor configured to detect a second height of the second frame sectionfrom the underlying surface; a third sensor coupled to the third framesection, the third sensor configured to detect a third height of thethird frame section from the underlying surface; a control unit disposedin electrical communication with the first sensor, the second sensor,and the third sensor, the controller operably controlling the firstactuator, the second actuator and the third actuator; wherein, thecontrol unit compares the first height, the second height, and the thirdheight to one another and determines if each height is equal to orwithin a threshold limit of one another; further wherein, when one ofthe first height, second height or third height is determined not to beequal to or within the threshold limit of the other two heights, thecontroller determines which frame section is uneven with the other twoframe sections and actuates the actuator that is coupled to the unevenframe section until the first height, second height, and third heightare equal or within the threshold limit of one another.

In one example of this embodiment, at least one of the first sensor,second sensor, and third sensor is ultrasonic, radar, optical, or laser.In a second example, the implement may include a fluid source forproviding hydraulic fluid; a first control valve operably controllablebetween an open position and a closed position, the first control valvefluidly coupling the fluid source to the first actuator in the openposition; a second control valve operably controllable between an openposition and a closed position, the second control valve fluidlycoupling the fluid source to the second actuator in its open position; athird control valve operably controllable between an open position and aclosed position, the third control valve fluidly coupling the fluidsource to the third actuator in its open position; and a flow pathdefined between the fluid source, the first actuator, the secondactuator, and the third actuator, the flow path fluidly coupling thefirst, second and third actuators in parallel with one another.

In a third example, the height of the first frame section iscontrollably adjusted by the first actuator when the first control valveis in its open position and the second and third control valves are intheir closed positions; the height of the second frame section iscontrollably adjusted by the second actuator when the second controlvalve is in its open position and the first and third control valves arein their closed positions; and the height of the third frame section iscontrollably adjusted by the third actuator when the third control valveis in its open position and the first and second control valves are intheir closed positions. In a fourth example, the implement may include afourth sensor, a fifth sensor, and a sixth sensor, the fourth sensorbeing coupled to the first frame section, the fifth sensor being coupledto the second frame section, and the sixth sensor being coupled to thethird frame section. In a fifth example, the first sensor is coupled ata front end of the first frame section and the fourth sensor is coupledat a rear end thereof, the first sensor detecting a front height of thefirst frame section and the fourth sensor detecting a rear height of thefirst frame section; the second sensor is coupled at a front end of thesecond frame section and the fifth sensor is coupled at a rear endthereof, the second sensor detecting a front height of the second framesection and the fifth sensor detecting a rear height of the second framesection; and the third sensor is coupled at a front end of the thirdframe section and the sixth sensor is coupled at a rear end thereof, thethird sensor detecting a front height of the third frame section and thesixth sensor detecting a rear height of the third frame section.

In a further example, the implement may include a linkage pivotably toone of the first, second or third sections of the frame for adjustablycontrolling a pitch of the frame; and a linkage actuator coupled to thelinkage for adjusting a length of the linkage; wherein, if a frontheight of one of the frame sections is detected not to be equal to orwithin a threshold limit of the rear height of the respective framesection, the control unit operably actuates the linkage actuator toadjust the length of the linkage until the front height is equal to orwithin the threshold limit of the rear height. In yet a further example,the implement may include a fluid circuit fluidly coupled to a fluidsource, the fluid circuit including a control valve disposed in fluidcommunication with the linkage actuator; wherein, the control valve isoperably controlled to actuate the linkage actuator between a retractedposition and an extended position.

In a second embodiment a work implement includes a transverselyextending frame including a front end and a rear end; a hitch memberconfigured to couple to a work machine, the hitch member being coupledto the front end of the frame; a front wheel and a rear wheel coupled toand supporting the frame, the front wheel and rear wheel adapted to movealong an underlying surface; a front wheel arm coupled to the frontwheel and pivotably coupled to the front end of the frame at a firstpivot location; a rear wheel arm coupled to the rear wheel and pivotablycoupled to the rear end of the frame at a second pivot location; alinkage coupled to the front wheel arm and rear wheel arm, the linkageincluding a linkage actuator for adjustably controlling a length of thelinkage; a first sensor coupled to the frame at or near the first pivotlocation, the first sensor configured to detect a first height of theframe relative to the underlying surface; a second sensor coupled to theframe at or near the second pivot location, the second sensor configuredto detect a second height of the frame relative to the underlyingsurface; and a control unit disposed in electrical communication withthe first sensor and the second sensor, the control unit operablycontrolling the linkage actuator based on the detected first height andsecond height.

In a first example of this embodiment, wherein the linkage actuatorincludes an electric actuator, hydraulic actuator, or electro-hydraulicactuator. In a second example, the control unit compares the firstheight to the second height, and if the first height is not equal to orwithin a threshold limit of the second height, the linkage actuator iscontrollably actuated until the first height is equal to or within thethreshold limit of the second height. In a third example, a secondactuator coupled to the frame and the rear wheel arm, the secondactuator being actuated between a first position and a second positionto raise or lower the frame relative to the underlying surface.

In a fourth example, the frame includes a main frame and a sub-frame,the main frame including the first sensor and a first work tool, and thesub-frame including the second sensor and a second work tool; wherein,the linkage adapter is controllably actuated to maintain the main frameand sub-frame level with one another; wherein, the second adapter iscontrollably actuated to control a depth of the first work tool andsecond work tool relative to the underlying surface. In a fifth example,the frame includes a main frame, a first sub-frame, and a secondsub-frame, the main frame including the first sensor and a first worktool, the first sub-frame including the second sensor and a second worktool, and the second sub-frame including a third sensor and a third worktool; wherein, the linkage adapter is controllably actuated to maintainthe main frame, the first sub-assembly and the second sub-assembly levelwith one another; wherein, the second adapter is controllably actuatedto control a depth of the first work tool, the second work tool, and thethird work tool relative to the underlying surface.

In a sixth example, the frame includes at least a first frame section, asecond frame section, and a third frame section, where the first framesection is disposed between the second and third frame sections; a firstactuator coupled to the first frame section, a second actuator coupledto the second frame section, and a third actuator coupled to the thirdframe section; the first and second sensors coupled to the first framesection, the first sensor configured to detect a height of the front ofthe first frame section relative to the underlying surface and thesecond sensor configured to detect a height of the rear of the firstframe section relative to the underlying surface; a third and a fourthsensor coupled to the second frame section, the third sensor configuredto detect a height of the front of the second frame section relative tothe underlying surface and the fourth sensor configured to detect aheight of the rear of the second frame section relative to theunderlying surface; a fifth and a sixth sensor coupled to the thirdframe section, the fifth sensor configured to detect a height of thefront of the third frame section relative to the underlying surface andthe sixth sensor configured to detect a height of the rear of the thirdframe section relative to the underlying surface; wherein, the controlunit compares the heights detected by each sensor and adjustablycontrols the first actuator, the second actuator and the third actuatoruntil each height is equal to or within a threshold limit of oneanother.

In another example, each of the first frame section, the second framesection and the third frame section includes the linkage and linkageactuator; further wherein, the control unit operably controls thelinkage actuator on each frame section so that the height of the frontof each frame section is equal to or within a threshold limit of theheight of the rear of the respective frame section. In a furtherexample, each sensor includes a tilt sensor for detecting an angle ofthe respective frame section relative to the other two frame sections.In yet a further example, the implement includes a fluid circuit fluidlycoupled to a fluid source, the fluid circuit including a control valvedisposed in fluid communication with the linkage actuator;

wherein, the control valve is operably controlled to actuate the linkageactuator between a retracted position and an extended position.

In another embodiment, a method is provided for leveling an agriculturalimplement having a transversely extending frame forming a center framesection, a first frame section disposed on one side of the center framesection, and a second frame section disposed on an opposite side of thecenter frame section, the method including providing a fluid source, acontrol unit, one or more actuators coupled to each frame section, aplurality of sensors coupled to each frame section, and a plurality oftools coupled to each frame section; detecting a height of the firstframe section relative to an underlying surface with a first sensor ofthe plurality of sensors, a height of the second frame section relativeto the underlying surface with a second sensor of the plurality ofsensors, and a height of the center frame section relative to theunderlying surface with a third sensor of the plurality of sensors;comparing the height of the first frame section, the height of thesecond frame section, and the height of the center frame sectionrelative to one another by the control unit; and determining an unevenframe section based on the comparing step if the height of one of theframe sections is not equal to or within a threshold limit of theheights of the other two frame sections; wherein, when the height of oneof the frame sections is determined not to be equal to or within athreshold limit of the heights of the other two frame sections, themethod further includes fluidly coupling the fluid source to a firstactuator if the height of the first frame section is uneven with theother two frame sections, to a second actuator if the height of thesecond frame section is uneven with the other two frame sections, or toa third actuator if the height of the center frame section is unevenwith the other two frame sections; actuating the respective actuatorcorresponding to the uneven frame section until the height of each framesection is equal to or within a threshold limit of one another; andleveling the center frame section, first frame section, and second framesection relative to one another.

In one example of this embodiment, the method includes providing alinkage coupled to each frame section, a linkage actuator coupled toeach linkage, and a fourth sensor of the plurality of sensors coupled toa front end of one of the center, first, and second frame sections,wherein the first sensor is coupled to a rear end of the first framesection, the second sensor is coupled to a rear end of the second framesection, and the third sensor is coupled to a rear end of the centerframe section; detecting a height of the front end of the respectiveframe section relative to the underlying surface; comparing the detectedheight of the front end of the respective frame section with the heightof the rear end of the same frame section; and determining if the heightof the front end is equal to or within a threshold limit of the heightof the rear end of the same frame section; wherein, if the height of thefront end is not equal to or within the threshold limit of the height ofthe rear end, the method further including controllably actuating thelinkage actuator of the respective frame section by the control unit;and adjusting a length of the linkage of the respective frame section bythe linkage actuator until the height of the front end is equal to orwithin the threshold limit of the height of the rear end of therespective frame section.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned aspects of the present disclosure and the manner ofobtaining them will become more apparent and the disclosure itself willbe better understood by reference to the following description of theembodiments of the disclosure, taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 is an elevated view of one embodiment of an agriculturalimplement;

FIG. 2 is a diagram of an electronic control system of a work machineand the agricultural implement of FIG. 1 ;

FIG. 3 is a diagram of a hydraulic control system of the work machineand agricultural implement of FIG. 2 ;

FIG. 4 is a chart of valve and cylinder primary response for tool depthcontrol;

FIG. 5 is a chart of valve and cylinder secondary response for tooldepth control;

FIG. 6 is an elevated view of another embodiment of an agriculturalimplement;

FIG. 7 is an elevated view of a further embodiment of an agriculturalimplement;

FIG. 8 is a side view of an agricultural implement;

FIG. 9 is a schematic of an agricultural implement; and

FIG. 10 is a diagram of a hydraulic control system of a work machine andagricultural implement.

Corresponding reference numerals are used to indicate correspondingparts throughout the several views.

DETAILED DESCRIPTION

The embodiments of the present disclosure described below are notintended to be exhaustive or to limit the disclosure to the preciseforms in the following detailed description. Rather, the embodiments arechosen and described so that others skilled in the art may appreciateand understand the principles and practices of the present disclosure.

Referring to FIG. 1 , an agricultural implement 100 such as a fieldcultivator is shown. The implement 100 is designed to couple to a workmachine and perform a work function. For example, the implement mayinclude work tools that penetrate into soil for aerating the soil beforeplanting or uprooting weeds after planting. The implement 100 may beattached to a work machine or tractor (not shown) by a hitch assembly112 such as a three-point hitch or a drawbar attachment. The hitchassembly 112 includes a hitch frame member 114 that extendslongitudinally in a direction of travel for coupling to the work machineor tractor.

The agricultural implement 100 may include a transversely-extendingframe that forms multiple frame sections. In FIG. 1 , for example, theimplement 100 includes a main or center frame 102. The main frame 102 iscoupled to the hitch assembly 112 as shown. A first frame section orfirst inner frame 104 is disposed to one side of the main frame 102, anda second frame section or second inner frame 106 is disposed to anopposite side thereof. In addition, a third frame section or first outerframe 108 is disposed to an outside of the first inner frame 104, and afourth frame section or second outer frame 110 is disposed to an outsideof the second inner frame 106. Each frame section may be pivotablycoupled to the frame section adjacent thereto. The first inner frame104, for example, may be pivotably coupled to the main frame 102 and thefirst outer frame 108. Similarly, the second inner frame 106 may bepivotably coupled to the main frame 102 and the second outer frame 110.

The implement 100 may be supported by a plurality of wheels. Forexample, a pair of front wheels 116 are coupled to the frame at a frontend thereof. The main frame 102 may be supported by a first pair ofwheels 118 and a second pair of wheels 120. The first inner frame 104may be supported by a third pair of wheels 130 and the second innerframe 106 may be supported by a fourth pair of wheels 136. Likewise, thefirst outer frame 108 may be supported by a fifth pair of wheels 142 andthe second outer frame 110 may be supported by a sixth pair of wheels148. While each section is shown being supported by a different pair ofwheels, this is only shown in the illustrated embodiment. In otherembodiments, there may be only a single wheel supporting each framesection. In a different embodiment, there may be more than a pair ofwheels supporting each frame section. Moreover, the implement 100 mayinclude more than the front wheels 116. For instance, there may be backwheels disposed near the rear of the implement for additional support.

In the illustrated embodiment of FIG. 1 , the agricultural implement 100may include a plurality of actuators for controlling movement of theframe. Each actuator may be a hydraulic actuator, electric actuator, orany other known actuator. Moreover, each actuator may include an outerbody or cylinder in which a rod or piston moves between an extendedposition and a retracted position. In FIG. 1 , the main frame 102includes a first actuator 122 and a second actuator 124. The first pairof wheels 118 may be coupled to the main frame 102 via a rock shaft (notshown) that may be hydraulically actuated by the first actuator 122. Thesecond pair of wheels 120 may be coupled to the main frame 102 viaanother rock shaft (not shown) that may be hydraulically actuated by thesecond actuator 124. The actuators can raise or lower the main frame 102relative to the wheels 118, 120, as will be described below.

The first inner frame 104 may include an actuator 132 for raising orlowering the first inner frame 104. Similarly, the second inner frame106 may include an actuator 138 for controlling a raising or loweringmovement of the second inner frame 104. The first outer frame 108 mayinclude an actuator 144 and the second outer frame 110 may include anactuator 150. The actuator 144 may control raising and lowering of thefirst outer frame 108 and the actuator 150 may control raising andlowering of the second outer frame 110.

In FIG. 1 , the main frame 102 includes a plurality of main framemembers 126. A plurality of tools 152 may be coupled to the main framemembers 126 for engaging a ground surface or soil upon which theimplement travels. Similarly, the first inner frame 104 includes aplurality of first inner frame members 128, the second inner frame 106includes a plurality of second inner frame members 134, the first outerframe 108 includes a plurality of first outer frame members 140, and thesecond outer frame 110 includes a plurality of second outer framemembers 146. Each of these frame members may include a plurality of worktools 152 coupled thereto.

While FIG. 1 represents an illustrated embodiment of an agriculturalimplement with five frame sections, this disclosure is not limited tothis embodiment. Other embodiments may include only three sections witha main frame and two outer frames. Alternatively, there may be more thanfive frame sections in further embodiments. Thus, this disclosure is notlimited to any number of frame sections, and the teachings herein may beapplicable to any multi-section implement.

Referring to FIG. 2 , an electronic control system 200 is shown of anagricultural implement 204 similar to the one described above and shownin FIG. 1 . Where applicable, reference numbers are repeated in FIG. 2as first addressed above with reference to FIG. 1 . In FIG. 2 , a workmachine 202 and the implement 204 are shown. The work machine 202 mayinclude a frame or chassis supported by a plurality of ground-engagingmechanisms (not shown) such as wheels. An operator's cab (not shown) maybe mounted to the frame and an operator may control the work machine 202therefrom. To do so, the work machine 202 may include a plurality ofcontrols (not shown) such as joysticks, levers, switches, knobs, asteering wheel, pedals, and the like. A controller 206 may beelectrically coupled to the plurality of controls, and the controller206 may control the functionality of the work machine 202.

Moreover, a user interface 208 may be disposed in the operator's cab.The user interface 208 may include a display 210 for displaying variouscharacteristics of the work machine such as, but not limited to, speed,fluid temperatures, fluid pressures, direction of travel, etc. Thedisplay 210 may be a touchscreen display that allows the operator tocontrol certain functions of the machine 202 by touching a button on thedisplay 210. Other uses of the user interface are available and thisdisclosure is not intended to be limited in any way with respect to thefunctionality of the operator controls or user interface 208.

The user interface 208 may also include controls for controlling theimplement 204, such as movement of the frame or setting a tool depth.For example, the operator may desire to raise or lower the main frame102 of the implement. To do so, the operator may input an instructionthrough the user display 208 which is received by the controller 206.The controller 206 may communicate with an electronic control unit (ECU)212 of the implement 204 via a wireless or control area network (CAN)214. A CAN is a vehicle bus standard designed to allow microcomputersand other electronic devices to communicate electronically with eachother in applications without a host computer. Here, the machinecontroller 206 may send an instruction to the implement ECU 212 to raiseor lower the main frame 102. As will be described, the ECU 212 may beprogrammed to execute this instruction and raise or lower the main frame102 or any other frame section of the implement.

Referring to FIGS. 1 and 2 , the ECU 212 may be in electricalcommunication with a plurality of sensors (e.g., rotary, Hall Effect)that are disposed at various locations on the implement 204. Forinstance, a first sensor 216 may be disposed at a location on the mainframe 102 for detecting rotation of the rock shaft (not shown) which isconnected to the first pair of wheels 118. A second sensor 218 may bedisposed at a location on the main frame 102 for detecting rotation ofthe rock shaft connected to the second pair of wheels 120. Each sensormay be a rotary sensor, a Hall Effect sensor, or any other type ofsensor. In addition, the first and second sensors may detect rotation ofthe rock shafts and communicate accordingly to the ECU 212. The ECU inturn can adjust or set the height of the main frame 102.

For example, a height of the wheels can be used to set a frame height.As described above, a plurality of ground-engaging work tools 152 may becoupled to the main frame 102. By controlling or actuating the firstactuator 122 and the second actuator 124, the height of the main frame102 can change for setting a depth of the work tools 152 into a groundsurface or soil upon which the implement 100 travels. The first sensor216 and the second sensor 218 may be positioned appropriately to detectrotation of the rock shaft. As the rock shaft rotates, the actuatorextends or retracts. The ECU 212 may be programmed such that when thefirst actuator 122 and second actuator 124 are fully extended the mainframe height is at a first height, and when the actuators are fullyretracted the main frame height is at a second height. As the actuatorcylinders extend and retract, the first pair of wheels 118 and secondpair of wheels 120 can be raised or lowered, thereby adjusting theheight of the main frame 102.

Besides the sensors on the main frame, a third sensor 222 may bedisposed on the first inner frame 104 and detect a height of the thirdpair of wheels 130. A fourth sensor 226 may be disposed on or near thesecond inner frame 106 for detecting a height of the fourth pair ofwheels 136. A fifth sensor 230 may be disposed on or near the firstouter frame 108 for detecting a height of the fifth pair of wheels 142.Likewise, a sixth sensor 234 may be disposed on or near the second outerframe 110 for detecting a height of the sixth pair of wheels 148. Eachof the third, fourth, fifth, and sixth sensors may be in electricalcommunication with the ECU 212. Moreover, while six different sensorsare shown in FIG. 2 , the present disclosure is not limited to sixsensors. Other embodiments may include additional sensors for detectingand setting frame height. For those embodiments with fewer framesections, there may be fewer sensors. Each sensor detects a position ofwheels on each frame section, and thus the number of sensors may dependon the number of frame sections of a multi-section implement.

Referring to FIGS. 2 and 3 , the implement 204 may also include aplurality of control valves for controlling movement of the overallframe and each independent frame section. As shown, a first controlvalve 220 may be in electrical communication with the ECU 212. The firstcontrol valve 220 may be used for adjusting the height of the overallframe or only the main frame 102. A second control valve 224 may be inelectrical communication with the ECU 212 for controlling a raising orlowering movement of the first inner frame 104. A third control valve228 may be in electrical communication with the ECU 212 for controllinga raising or lowering movement of the second inner frame 106. A fourthcontrol valve 232 may be in electrical communication with the ECU 212for controlling a raising or lowering movement of the first outer frame108. Moreover, a fifth control valve 236 may be in electricalcommunication with the ECU 212 for controlling a raising or loweringmovement of the second outer frame 110.

Each of the aforementioned control valves may be an electrohydrauliccontrol valve that is capable of moving between an open position and aclosed position. Each valve may include a solenoid (not shown) that isenergized by an electrical current or signal sent by the ECU 212 toinduce movement of the valve between the open and closed positions. Themovement of the control valves can adjust fluid flow to the differentactuators for controlling movement of the overall frame or eachindividual frame section, as will be described below.

Among other things, the present disclosure provides details of ahydraulic control system for achieving depth control of work tools andcontrolling movement of a multi-section frame of an agriculturalimplement. With multi-section frame implements such as the one shown inFIG. 1 , it is desirable to achieve uniform tool depth along eachsection. Each section may have different tolerances or there may be asmall leak in the actuator that controls movement of an individual framesection. In either case, it can be difficult to achieve uniform depthacross each frame section and therefore the implement can utilize itshydraulic control system (and other control systems) to monitor andmaintain uniform depth control.

In conventional hydraulic control systems, the two most common types ofdepth control systems are series hydraulic control and parallelhydraulic control. A series hydraulic control is typically a puremechanical system without any electronic control. Here, hydraulic fluidis supplied from a fluid source to a first or master actuator orcylinder. The master cylinder receives the full amount of fluid flow,and as the master cylinder is actuated, fluid is displaced from themaster cylinder and flows to the next-in-line actuator or cylinder. Inthis system, each actuator or cylinder is fluidly connected to oneanother in a series which allows for each cylinder to quickly receivefluid from the fluid source.

The series hydraulic control is ideal when it is necessary to raise theentire implement frame. However, it is not as desirable when only oneframe section needs to be raised or lowered. As a result, someimplements utilize the parallel hydraulic control. The parallelhydraulic control can include electronic control unlike the serieshydraulic control. In this type of control, valves are utilized tocontrol how fluid flows through the system. Fluid flows across eachsection in an equal amount so that fluid is available at each wheel toadjust a frame section height. The fluid source, however, only has alimited amount of fluid. Thus, when an operator wants to raise or lowera certain frame section, the parallel hydraulic control is capable ofproviding fluid to the actuator at that section but it may take muchlonger than in a series hydraulic control. It therefore can take longerto raise or lower a frame section, which can delay the operator fromperforming a desired function or operation. A slower system response isoften the result with a depth control system consisting of conventionalparallel hydraulic control.

Referring to FIG. 3 , the present disclosure provides a different typeof depth control system for the implement 204. Here, a combination ofthe series hydraulic control and parallel hydraulic control form ahybrid parallel-series hydraulic depth control system 300. In thissystem 300, additional hydraulics is added to obtain the benefits ofboth the series and parallel control while eliminating or reducing theproblems associated with each. In FIG. 3 , a fluid source 302 provideshydraulic fluid to the system 300. The fluid source 302 may be locatedon the work machine or tractor 202, and a hydraulic pump may supply thefluid to the implement. A fluid reservoir or tank 304 may also beprovided for fluid to return from the implement 204. The fluid source302 and fluid reservoir 304 may be fluidly coupled to one another.

The work machine or tractor 202 may also include a selective controlvalve 306 that is fluidly coupled to the fluid source 302. The valve 306may be any type of valve that selectively allows fluid to flow from thework machine 202 to the implement 204. The valve 306 may be anelectrohydraulic control valve that is controlled by the machinecontroller 206. For example, the controller 206 may be programmed toselectively open and close the control valve 206. If the work machine202 requires additional hydraulic fluid to perform an operation, thecontroller 206 may close the valve 306 and not permit fluid to flow tothe implement 204. In one embodiment, the selective control valve 306may be biased to its open position and thus may be referred to as anormally open control valve. In another embodiment, the valve 306 may bebiased to its closed position and thus be referred to as a normallyclosed valve.

In any event, hydraulic fluid may be supplied by the fluid source 302through the control valve 306 and to the implement 204 via a first flowpath 308 or pressure line. The first flow path 308 may be defined suchthat is passes through the first control valve 220 and to each of thefirst actuator 122 and second actuator 124. Moreover, when the first orsecond actuator is actuated, fluid displacement may result in fluidflowing through the first flow path to either the third actuator 132 orfourth actuator 138. Similarly, when either the third or fourth actuatorare actuated, the fluid displacement in the actuator may allow fluid toflow to the fifth actuator 144 or sixth actuator 150 via the first flowpath 308. In this embodiment, the first flow path 308 forms a serieshydraulic control in which each actuator is fluidly coupled to oneanother in series. This can allow an operator to raise or lower theentire frame of the implement 204, or raise or lower the main frame 102.

In the first fluid path 308 or pressure line, the first control valve220 may be biased in its open position. In this embodiment, the firstcontrol valve 220 is a normally open electrohydraulic control valve andthus hydraulic fluid can flow via the first fluid path 308 through thefirst control valve 220 without requiring any interaction by the ECU212. This again is similar to the series hydraulic control describedabove. In this disclosure, however, it is appreciated that in otherembodiments, the first control valve 220 may be a normally closedelectrohydraulic control valve. In these other embodiments therefore theECU 212 may be required to actuate or trigger the valve to its openposition. In a further embodiment, the first control valve 220 may notbe controlled by the ECU 212 or biased in either an open or closedposition, but rather pressure acting on either side of the valve mayactuate it between an open and closed position. Thus, different types ofvalves may be used in the embodiments described herein.

To control depth of the plurality of work tools 152, a second fluid path310 or pressure line may be provided. A node 314 may be provided wherethe first and second fluid paths intersect. The node 314 may be amanifold or T that allows fluid to flow through both lines. Thus, fluidcan flow from the fluid source 302 through the first fluid path 308 andthe second fluid path 310. As shown in FIG. 3 , however, the secondcontrol valve 224, the third control valve 228, the fourth control valve232, and the fifth control valve 236 may be biased in their closedpositions. Thus, fluid flowing through the second flow path is unable toflow through these other control valves until the ECU 212 selectivelyopens one of the control valves. If the ECU 212 selectively opens thesecond control valve 224, for example, then fluid can flow through thevalve 224 via the second flow path 310 and reach the third actuator 132.In doing so, the third actuator 132 may be controllably actuated toraise or lower the first inner frame 104 to adjust the depth of itsplurality of work tools 152.

Similar to the first control valve 220 described above, this disclosureis not intended to limit the different control valves to any particularbiased position. Thus, the second control valve 224, the third controlvalve 228, the fourth control valve 232, and the fifth control valve 236may be biased or pre-disposed in a normally open position or a normallyclosed position. Alternatively, these control valves may be actuated byfluid pressure acting on either side of each respective valve, therebynot requiring intervention by the ECU 212. Other embodiments thatincorporate any type of valve may be used to achieve the operation ofthe control system 300.

The control system 300 may also include a third fluid path 312 or returnpressure line. Each actuator may be designed to include at least twodifferent fluid ports. One port may be disposed on a base side of theactuator and the other port may be disposed on a rod side of theactuator. The third fluid path 312 is fluidly coupled to the fluidreservoir 304, the fifth actuator 144, and the sixth actuator 150. Anyfluid that flows through the first and second flow paths can thereforebe returned to the reservoir 304 via the third flow path 312. As aresult, a combination of the first and third flow paths and the secondand third flow paths can define a closed-loop hydraulic circuit.

As previously described, the first control valve 220 does not requireany electronic intervention or control by the ECU 212 to permit fluidflow through the series portion of the system 300. On the other hand,the second control valve 224, the third control valve 228, the fourthcontrol valve 232, and the fifth control valve 236 are electricallycontrolled by the ECU 212 to permit fluid flow through the parallelportion of the system 300. When an operator commands a raising orlowering movement of an individual frame section, the ECU 212 maycommand the first control valve 220 to its closed position and open oneof the normally-closed valves to allow fluid flow through the secondflow path 310 to the appropriate actuator for raising or lowering thedesired frame section. This type of control will be described withreference to FIGS. 4 and 5 .

Before turning to FIGS. 4 and 5 , however, the hydraulic control system300 of FIG. 3 includes a plurality of nodes or manifolds. As previouslydescribed, the first node 314 is an intersection point of the first andsecond flow paths. A second node 316 may be disposed in the first fluidpath 308 downstream of the first control valve 220. Here, the first flowpath 308 separates into two flow paths so that fluid can be supplied tothe first actuator 122 along one path and the second actuator 124 alonga second path.

A third node 318 is another intersection point of the first and secondflow paths, but it is located downstream of the second control valve224. Here, fluid may pass through the third node 318 and to the thirdactuator 132. A fourth node 320 is an intersection point of the firstand second fluid paths, but it is located downstream of the thirdcontrol valve 228 and upstream from the fourth actuator 138. A fifthnode 322 is another intersection point of the first and second flowpaths, but it is located downstream of the fourth control valve 232 andupstream from the fifth actuator 144. Lastly, a sixth node 324 providesa further intersection point of the first and second flow paths, but itis located downstream from the fifth control valve 236 and upstream ofthe sixth actuator 150. In the illustrated embodiment, each of thethird, fourth, fifth and sixth nodes are located between a differentcontrol valve and a different actuator. Unlike the first and secondnodes, however, fluid may only flow through either the first or secondflow path when passing through each of the third, fourth, fifth andsixth nodes due to the ECU selectively opening or closing the differentcontrol valves.

Referring to FIG. 4 , control logic for controlling the implement isprovided. Here, the logic includes a primary control valve responsetable 400 and a primary actuator or cylinder response table 402. In thevalve response table 400, there are rows that refer to a type ofresponse commanded by an operator such as raise or lower the overallimplement frame (e.g., “Raise Overall”), raise or lower the main frame102 (e.g., “Raise MF”), raise or lower the first inner frame 104 (e.g.,“Raise LIW”), raise or lower the second inner frame 106 (e.g., “RaiseRIW”), raise or lower the first outer frame 108 (e.g., “Raise LOW”), andraise or lower the second outer frame 110 (e.g., “Raise ROW”). In thistable, “R” refers to right and “L” refers to left when looking at theimplement from its front rearward. Moreover, “I” refers to inner and “O”refers to outer.

The other rows in the valve response table 400 indicate the differentframe sections of the implement. Here, “RMF” and “LMF” refer to rightmain frame and left main frame, respectively. In FIG. 1 , this is simplythe main frame 102. “LIW” and “RIW” refer to left inner wing and rightinner wing, respectively. The left inner wing is the first inner frame104 and the right inner wing is the second inner frame 106 as shown inFIG. 1 . Further, “LOW” and “ROW” refer to left outer wing and rightouter wing, respectively, which corresponds with the first outer frame108 and the second outer frame 110, respectively. In this table 400, theresponse of each control valve is illustrated as either being in itsopen position “O” or closed position “C”.

For purposes of table 400, the first control valve 220 has a responseindicated with reference number 404, the second control valve 224 has aresponse indicated as reference number 408, the third control valve 228has a response indicated as reference number 406, the fourth controlvalve 232 has a response indicated as reference number 412, and thefifth control valve 236 has a response indicated as reference number410.

In the primary actuator or cylinder table 402, the rows and columns aresimilar to those in table 400. Here, however, the actuator is beingcharacterized as either being in its extended position “E” or itsretracted position “R”. In the event the actuator is not actuated, thenneither an “E” or an “R” appears in the respective box. The response ofthe first and second actuators is represented by reference number 414.The response of the third actuator 132 is represented by referencenumber 418, the response of the fourth actuator 138 is represented byreference number 416, the response of the fifth actuator 144 isrepresented by reference number 422, and the response of the sixthactuator 150 is represented by reference number 420 in FIG. 4 .

Referring to FIG. 5 , the control logic for controlling the implementmay also include a secondary control valve response table 500 and asecondary actuator or cylinder response table 502. In the secondaryvalve response table 500, a first column 504 provides for differentresponses or reactions required of the different control valves. Here,if a secondary response is required, the column 504 illustrates a “Y”,and if no secondary response is required then the column 504 is shownwith a “N”. This will be further described below.

For purposes of table 500, the first control valve 220 has a responseindicated with reference number 506, the second control valve 224 has aresponse indicated as reference number 510, the third control valve 228has a response indicated as reference number 508, the fourth controlvalve 232 has a response indicated as reference number 514, and thefifth control valve 236 has a response indicated as reference number512.

In the secondary actuator or cylinder table 502, the rows and columnsare similar to those in table 500. A first column 516 provides fordifferent responses or reactions required of the different actuators orcylinders. If no response is required, then the row is left blank undercolumn 516. If, however, a response is required, then the type ofresponse is provided. As is similar to table 402, each actuator is beingcharacterized as either being in its extended position “E” or itsretracted position “R” in table 502. In the event the actuator is notactuated, then neither an “E” or an “R” appears in the respective box.The response of the first and second actuators is represented byreference number 518. The response of the third actuator 132 isrepresented by reference number 522, the response of the fourth actuator138 is represented by reference number 520, the response of the fifthactuator 144 is represented by reference number 526, and the response ofthe sixth actuator 150 is represented by reference number 524 in FIG. 5.

Since the hydraulic control system 300 of FIG. 3 is a hybridparallel-series control, hydraulic fluid flows through the system 300from the innermost frame section (e.g., the main frame 102) to theoutermost frame section (e.g., the first outer frame 108 or the secondouter frame 110). Since the third flow path or return line 312 is onlyfluidly coupled to the first and second outer frames, the fluid can flowthrough the first flow path 308 or second flow path 310 until it worksits way into the return line 312 and returns to the fluid reservoir 304.As will be described, the control system 300 may require two responseswhen independently actuating the third or fourth actuator and raising orlowering either the first inner or second inner frame. This is becauseas fluid is provided to the third actuator 132, for example, to raise orlower the first inner frame 104, the resulting raising or loweringmovement of the first inner frame 104 induces a similar raising orlowering movement of the first outer frame 108 as well. Fluid that isused to actuate the third actuator 132 then flows to the fifth actuator144, and the fifth actuator 144 is actuated to allow the fluid to bereturned to the fluid reservoir via the third fluid path 312.Controlling the fifth actuator 144 therefore results in a secondaryaction or response to enable the entire frame to be balanced out andcontrolled at approximately the same height (or same tool depth).

The ECU 212 may have the control logic of FIGS. 4 and 5 stored in amemory unit thereof. A processor of the ECU 212 may then execute thecontrol logic as commanded by the operator. This logic may also be partof a software program or algorithm used by the ECU 212 when controllingthe frame height of the implement.

As described above, when the operator desires to raise or lower theentire frame or only the main frame 102, then there is no interaction bythe ECU 212 to control the control valves. This is the case when thefirst control valve 220 is normally or biased in its open position, andthe other control valves are biased in their normally closed position.If, however, in a different embodiment the first control valve 220 is anormally closed valve, then the ECU 212 would intervene andelectronically control the valve 220 to its open position.

In the primary valve table 400 of FIG. 4 , it is shown that a command toraise or lower the entire frame requires the first control valveresponse 404 to be open “O” and the other control valves to be closed“C”. The same is true if the ECU 212 receives an instruction to raise orlower the main frame 102. Again, the first control valve response 404 isto be open and the other control valve responses are closed. Moreover,with respect to the cylinder response table 402, whenever the entireframe or a frame section is controlled in a raised movement, therespective actuator or actuators are controlled to their extendedposition, and if a lowering instruction is received then the actuator oractuators are controlled to their retracted positions. This is clearlyshown in table 402 of FIG. 4 where the responses of all six actuators isto extend when raising the entire frame and all six actuators retractwhen lowering the entire frame.

The same is true whenever a single frame section is raised or lowered.For example, when the first outer frame 108 is raised, the correspondingactuator response 422 is to extend. As shown in table 402, when thefirst outer frame 108 is lowered, the corresponding actuator response422 is to retract.

Example 1

In a first example of the present disclosure, the operator sets a targetdepth for the plurality of tools coupled to each frame section of theimplement to 3 inches. During operation, the first sensor 216 and secondsensor 218 detect the main frame 102 is at a depth of 3.5 inches. Uponcommunicating this to the ECU 212, the ECU 212 may compare the detecteddepth to the target depth. In some instances, a threshold may beestablished such that the detected depth has to be greater than athreshold amount different from the target depth before the ECU 212takes any corrective action. For this example, suppose the threshold is0.25 inches and thus the detected depth of 3.5 inches exceeds thethreshold amount.

In order to adjust the main frame 102 and raise it from 3.5 inches tothe target depth of 3.0 inches, the ECU 212 may be programmed based onthe logic of FIGS. 4 and 5 . Here, in table 400 the first control valve220 needs to be in its open position and the other control valves intheir closed position. As described above, the first control valve 220is normally open and the other control valves are normally closed. Thus,there is no required action on behalf of the ECU 212 other than monitorthe first and second sensors until the first actuator 122 and secondactuator 124 are actuated to their extended positions to raise the mainframe 102. As shown in table 402, the other actuators are also actuatedto their extended positions when raising the main frame 102.

Once the main frame 102 is raised to the target depth of 3 inches, theECU 212 receives communications from the other sensors indicating thatboth inner frames and both outer frames have also been raised by 0.5inches to 2.5 inches. Thus, corrective action is required. This isfurther shown in FIG. 5 in column 504 where it indicates a correctiveresponse is required. According to table 502, the corrective response isto close the first control valve 220. In addition, the second controlvalve 224 and third control valve 228 may be opened to allow the thirdactuator 132 and fourth actuator 138 to be actuated to lower the firstand second inner frames. As described above, with the parallel hydrauliccontrol, by lowering the first inner frame 104 a resulting action is thefirst outer frame 108 also lowers by approximately the same amount.Moreover, by lowering the second inner frame 106, the second outer frame110 also lowers by approximately the same amount. Thus, each framesection is operably controlled to the target depth.

Example 2

In a second example, the operator may set the target depth to 3 inchesagain. During operation, the ECU receives a signal from the fifth sensor230 indicating that the first outer frame 108 is detected at 2.5 inchesdeep. If the threshold is 0.25 inches, the detected depth exceeds thethreshold and is not at the target depth. Thus, the ECU 212 can operablycontrol the hydraulic fluid from the fluid source 302 through the secondflow path 310 and to the fourth control valve 232. Moreover, based ontable 402, to lower the first outer frame 108 the appropriate valveresponse 412 is close the first control valve, maintain the secondcontrol valve 224, the third control valve 228, and the fifth controlvalve 236 in their closed positions, and open the fourth control valve232. According to table 402, the fifth actuator 144 is actuated to itsretracted position to operably control a lowering movement of the firstouter frame 108 to the target depth. Once the first outer frame 108reaches the target depth, the hydraulic fluid can return via the thirdflow path 312 to the fluid reservoir 304. In addition, as shown intables 500 and 502, there is no secondary corrective action required. Inthis example, each of the five frame sections should be set at thetarget depth.

Example 3

In a third example, the operator commands a target depth of 3 incheswith a threshold amount of 0.25 inches. In this example, suppose the ECUreceives a signal from the fourth sensor 226 indicating that the firstinner frame 106 is at a depth of 3.5 inches. Since the detected depth isnot at the target depth of 3 inches, and it is outside of the thresholdrange of 0.25 inches, the ECU 212 can execute the logic set forth intables 400, 402, 500, and 502 to raise the second inner frame 106 by 0.5inches.

According to table 400, to raise the second inner frame 106 requires aprimary valve response 406 of closing the first control valve 220,opening the third control valve 228, and maintaining the other controlvalves in their closed positions. By doing so, hydraulic fluid cannotflow through the first control valve 220 via the first flow path, andinstead flows through the second flow path 310. Fluid passes through thethird control valve 228 and the fourth actuator 138 may be actuated toits extended position as shown in table 402.

As the second inner frame 106 is raised to the target depth of 3 inches,table 502 indicates a secondary corrective action is necessary. In thiscase, by raising the second inner frame 106 by 0.5 inches, the secondouter frame 110 is also raised by 0.5 inches to 3.5 inches. Again, thisdetected depth is not the target depth and exceeds the threshold rangeof 0.25 inches. As such, the ECU 212 takes corrective action to lowerthe second outer frame 110. As shown in table 500, the correspondingresponse is to maintain the first control valve 220, the second controlvalve 224, and the fourth control valve 232 in their closed positions.In addition, the ECU 212 operably controls the third control valve 228from its open position to its closed position, and operably controls thefifth control valve 236 from its closed position to its open position.This allows fluid to flow through the fifth control valve 236 and to thesixth actuator 150. The sixth actuator can be actuated to lower thesecond outer frame 110 to the target depth of 3 inches, and fluid can bereturned to the fluid reservoir 304 via the third fluid path 312.

The above examples are provided only to illustrate how the ECU 212 maybe programmed to control the different control valves and actuators formoving the entire frame and each frame section as commanded by theoperator. It should be appreciated that in other embodiments, and asdescribed above, one or more of the control valves may be biased in adifferent position than as shown and described above. As such, the ECU212 may be programmed accordingly to raise or lower the frame or framesections utilizing the parallel-series hydraulic control system asdescribed herein.

Referring to FIG. 6 , a different embodiment of an agriculturalimplement 600 is shown. In this embodiment, reference numbers previouslydescribed above and shown in FIGS. 1-5 refer to the same features inFIG. 6 . This implement 600 is capable of performing a cultivatingoperation, although the use or function of the implement is not limitingto this embodiment. The implement is shown being formed by a multiplesections or frame. For instance, a first or centrally located frame 602is positioned towards the middle of the implement 600. A second frame604 and a third frame 606 are disposed on opposite sides of the mainframe 602. Although only three frame sections are shown in FIG. 6 ,other embodiments may include more than three sections. Alternatively,one or two frame sections are also possible.

Similar to the previously described embodiments, the first frame section602 includes one or more frame members 608 that form the entire section602. Likewise, the second frame section 604 includes one or more framemembers 610, and the third frame section 606 includes one or more frame612. In at least one embodiment, front wheels 116 and rear wheels 614may be coupled to the frame members.

In the embodiment of FIG. 6 , work tools 628 are provided for performinga work function (e.g., the cultivating operation). For purposes of thisdisclosure, any type of work tool may be used for performing a desiredfunction. In this embodiment, there are a plurality of tools 628provided for performing the work function. In a different embodiment,there may only be one work tool depending upon the type of work functionbeing executed. Here, the plurality of work tools 628 are coupled to asub-frame, and the sub-frame is coupled to one of the frame members ofeither the first frame 602, the second frame 604, or the third frame606.

In FIG. 6 , a first sub-frame 616, a second sub-frame 618, a thirdsub-frame 620, a fourth sub-frame 620, a fifth sub-frame 620, and asixth sub-frame 620 are shown. There may be any number of sub-frames inother embodiments. Moreover, each sub-frame may be coupled at a locationbelow the main frame. For purposes of this embodiment, the first framesection 602, the second frame section 604, and the third frame section606 may be collectively referred to as a main frame. Thus, the pluralityof tools 628 are coupled to one of the sub-frames beneath the mainframe.

Each sub-frame may be pivotally coupled to the main frame via anactuator. As such, the respective sub-frame may be pivoted with respectto the main frame. In FIG. 6 , the first sub-frame 616 is pivotallycontrolled and coupled to the first frame section 602 by a firstactuator 630. Similarly, the second sub-frame 618 may be pivotallycontrolled and coupled to the first frame section 602 by a secondactuator 630. Although not shown, the third sub-frame 620 and fifthsub-frame 624 may each be coupled by an independent actuator to thesecond frame section 604. Similarly, and also not shown, the fourthsub-frame 622 and the sixth sub-frame 626 may each be coupled by anindependent actuator to the third frame section 606.

Each of the aforementioned actuators may be a hydraulic actuator thatfunctions similarly to those described above and shown in FIGS. 1-3 .Alternatively, other types of actuators may be used such as electricactuators, mechanical actuators, and any other known type of actuator.In the embodiment of FIG. 6 , each actuator is a hydraulic actuatorcontrolled by hydraulic fluid. Moreover, each actuator includes acylinder (not shown) having a first end coupled to the main frame (e.g.,the respective frame section 602, 604, 606) with a rod (not shown) orother member that telescopically moves with respect to the cylinderbased on hydraulic pressure within the cylinder. The rod or other membermay be coupled to the respective sub-frame to allow pivotal movement ofthe sub-frame with respect to the main frame. The sub-frame can pivotwith respect to the main frame as the actuator is controlled between itsextended and retracted positions.

As the sub-frame pivots with respect to the main frame, the angle ofeach of the plurality of tools 628 coupled to the sub-frame changes withrespect to a direction of travel identified by arrow 634 in FIG. 6 . Theimplement 600 may be driven along the direction of travel 634 by amachine or tractor, as described above. In one example, the angle ofeach tool 628 may be changed by 60° or less. In another example, theangle may be changed by 30° or less. In a further example, the angle maybe changed by 10° or less with respect to the direction of travel 634.In yet a further example, the angle of each tool 628 may be variedbetween 0-10° with respect to the direction of travel 634. Other anglesof variation are further contemplated in this disclosure, and may dependon the type of implement, tool, or work function.

The variable angle setting of each sub-frame may be controlled by theECU 212. This may be controlled hydraulically according to theembodiment shown in FIG. 3 . Here, each sub-frame may be coupled to themain frame (e.g., the first frame section 602, the second frame section604, and third frame section 606) via an actuator. Hydraulic fluid canbe controlled to the different actuators in either a series or parallelcontrol. Thus, the variable angle control setting is handled in a mannersimilar to the depth control setting as previously described.

For sake of clarity, fluid flow may be directed to a control valvesimilar to that of the first control valve 220. If the ECU 212 controlsthe control valve to its open position, hydraulic fluid can flow in aseries path to each actuator for adjusting the angle of each sub-framerelative to the main frame. If, however, the ECU 212 only wants tocontrol the angle setting of one sub-frame, the ECU 212 may close thecontrol valve and open a different control similar to the other controlvalves (224, 228, 232, 236) described above. As such, a parallel flowpath is formed to enable hydraulic fluid to flow to the actuator thatcontrols pivotal movement of the desired sub-frame. A secondarycorrective action, similar to that described in Example 3 above, mayalso be required and achieved according to the same teachings andprinciples above. In addition, any of the control valves in thisembodiment may be normally open or closed, and the same principles applyfor achieving series-parallel hydraulic control of the implement.

Thus, the angle of any one sub-frame may be hydraulically controlled viaparallel control to a desired setting with respect to the direction oftravel 634. Moreover, all of the sub-frames can be angularly varied withrespect to the main frame via series control, as described above.

In a further embodiment, the depth in which a tool or plurality of tools628 coupled to a sub-frame may be controllably varied with respect to aground surface. In this embodiment, the sub-frame may be coupled to arock shaft that rotates or pivots in a substantially vertical direction.The rock shaft may also be coupled to one end of an actuator, whereasthe opposite end of the actuator is coupled to the main frame. In thisembodiment, the cylinder of the actuator is coupled to the main frame,and the cylinder rod is coupled to the rock shaft. As the cylinder rodextends and retracts with respect to the cylinder, the rock shaft isrotated. As the rock shaft rotates, the sub-frame moves up or down tochange the depth in which the tool or plurality of tools 628 penetratesinto the underlying ground surface.

Similar to the previously described embodiments, the ECU 212 can controla position of a control valve between an open and closed position. Inthe open position, hydraulic fluid can flow through a first flow paththrough the control valve to provide a series hydraulic control. Theseries hydraulic control allows hydraulic fluid to flow to each of aplurality of actuators for operably adjusting the depth of tools 628coupled to different sub-frames. In FIG. 6 , for example, hydraulicfluid can flow to the first actuator 630 and second actuator 632 inseries so that the plurality of tools 628 mounted to the first sub-frame616 and second sub-frame 618 may be controllably adjusted to differentdepths. In FIG. 6 , the aforementioned rock shafts are not shown, but inthis embodiment, a rock shaft would be coupled between the firstactuator 630 and the first sub-frame 616, and a different rock shaftwould be coupled between the second actuator 632 and the secondsub-frame 618. A similar arrangement may be provided with respect to thethird sub-frame 620, the fourth sub-frame 622, the fifth sub-frame 624,and the sixth sub-frame 626.

If, however, only one of the sub-frames needs to be adjusted to meet adesired tool depth, then parallel control may be used to achieve thedesired depth. Here, the control valve may be closed so that hydraulicfluid does not pass therethrough. With the valve closed, fluid may flowthrough a parallel flow path similar to that shown in FIG. 3 andidentified as the second flow path 310. The ECU 212 may operably controla different control valve so that fluid may flow through that particularcontrol valve and to the actuator that is able to adjust the height ofthe respective sub-frame. In FIG. 6 , for example, an actuator (notshown) may receive hydraulic fluid through the parallel flow path sothat the third sub-frame 620, the fourth sub-frame 622, the fifthsub-frame 624, or the sixth sub-frame 626 may be adjusted. As alsodescribed, depending upon which sub-frame is adjusted, a secondarycorrective action may be required in a similar manner as describedabove.

In an embodiment similar to the previous one, a tool or plurality oftools may be coupled directly to the rock shaft. In this embodiment,there may not be a sub-frame, but the tool or plurality of tools may beoperably controlled in a similar manner as previously described.

Another aspect of the present disclosure is the ability to level themachine and achieve a uniform and consistent tool depth regardless ofmachine width or firmness of the underneath ground or soil. Manyconventional tillage machines, for example, require manual adjustmentsvia turnbuckles and the like to achieve machine leveling. Otherconventional machines may include some degree of hydraulic leveling, buteven these machines require an operator or user to set or establish atarget level. This form of machine leveling often introduces human errorwhich leads to inconsistent and imprecise settings.

In addition, environmental conditions often make it difficult to achievemachine leveling. For instance, if a machine is first levelled on a flatconcrete slab, the machine may not be level from side-to-side across thewidth of the machine or from front-to-back due to changes in thefirmness of the soil or differences in tire deflection at variouslocations across the machine. In some instances, a tillage machine maystretch 40-90 feet in width, and the soil may be firm at one end of themachine but soft at the opposite end. The wheel or wheels at the end atwhich the soil is soft may sink into the soil more than the wheel orwheels at the opposite end, thus producing an uneven machine. Further,an operator's vision may be limited when detecting when the machine islevel. If a tool depth of 2-4 inches is desired and the tillage machineis 70 feet wide, the operator must evaluate and determine if the machine35 feet to either side is level with one another. If the operator is offby 0.5-1.0 inch, this can introduce error in the machine operation.

In the previously described embodiments, tool depth or depth controlsystems and methods are described. In these embodiments, a distance orposition between a wheel and frame to which the wheel is coupled weremade uniform across the width of the machine. In the embodiments ofFIGS. 7-10 , various systems and methods provide for uniform tool depthby establishing uniform frame height across the machine and in the foreand aft direction with respect to the ground or underlying surface.

Referring to FIG. 7 , an agricultural implement 700 such as a fieldcultivator is shown. Similar to the implement 100 of FIG. 1 , theimplement 700 is designed to couple to a work machine and perform a workfunction. For example, the implement may include work tools 726 thatpenetrate into soil for aerating the soil before planting or uprootingweeds after planting. The implement 700 may be attached at its front end712 to a work machine or tractor (not shown) by a hitch assembly 708such as a three-point hitch or a drawbar attachment. The hitch assembly708 includes a hitch frame member 710 that extends longitudinally in adirection of travel 750 for coupling to the work machine or tractor.

The agricultural implement 700 may include a transversely-extendingframe that forms multiple frame sections. In FIG. 7 , for example, theimplement 700 includes a main or center frame 702. The main frame 702 iscoupled to the hitch assembly 708 as shown. A first frame section 704 isdisposed to one side 716 of the main frame 702, and a second framesection 706 is disposed to an opposite or second side 718 thereof. Whilenot shown, other implements may include additional frame sectionscoupled to the first and second frame sections similar to that shown inFIG. 1 .

Each frame section may be pivotably coupled to the frame sectionadjacent thereto. The first frame section 704, for example, may bepivotably coupled to the main frame 702 so that it can be folded in anupright position or unfolded in the position shown in FIG. 7 .Similarly, the second frame section 706 may be pivotably coupled to themain frame 702 so that it can be folded in an upright position orunfolded in the position shown in FIG. 7 .

As shown in FIG. 7 , the implement 700 has a front end or side 712, arear end or side 714, a first side 716, and a second side 718. In thisdisclosure, the width of the implement is defined between the first andsecond sides, and the fore-and-aft direction refers to the length ordistance between the front end 712 and rear end 714 of the implement700.

The implement 700 may be supported by a plurality of wheels. Forexample, a plurality of front wheels 718 are coupled at the front end712 thereof. The main frame section 702 includes a main frame member 720which is supported by at least one of a first set of wheels 732 and asecond set of wheels 734. The first frame section 704 may include afirst frame member 722 which is supported by at least a third set ofwheels 730. In addition, the second frame section 706 may include asecond frame member 724 which is supported by a fourth set of wheels736. While each section is shown being supported by a different set ofwheels, this is only shown in the illustrated embodiment. In otherembodiments, there may be only a single wheel supporting each framesection. In a different embodiment, there may be more than two wheelssupporting each frame section. Thus, for purposes of this disclosure, aset of wheels may include one or more wheels. Further, the first set ofwheels 732 and second set of wheels 734 may include two wheels each. Oneof the two wheels may support the main frame section 702 Moreover, theimplement 100 may include more than the front wheels 728.

In the illustrated embodiment of FIG. 7 , a plurality of sensors arecoupled to the implement 700 at locations on or near each wheel module.The plurality of sensors may be ultrasonic, optical, radar, or lasersensors. Other sensors may include position sensors (e.g.,potentiometer, hall effect, etc.). The plurality of sensors may becoupled to the different frame members and positioned such that eachsensor is oriented towards the ground or underlying surface. Each sensorcan therefore detect the distance between its location and the ground.In FIG. 7 , the plurality of sensors may include a first sensor 738, asecond sensor 740, and a third sensor 742. Each of these sensors may bepositioned toward the rear 714 of the implement 700, and at or near eachof the sets of rear wheels 730, 732, 734, 736. The plurality of sensorsmay also include a fourth sensor 744, a fifth sensor 746, and a sixthsensor 748. Each of these sensors may be positioned toward the front 712of the implement 700.

The first sensor 738 and the fourth sensor 744 may each be coupled tothe first frame section 704 at the front end 712 and rear end 714,respectively. The second sensor 740 and fifth sensor 746 may be coupledto the main frame section 702 at the front end 712 and rear end 714,respectively. As shown, the second sensor 740 may actually include twosecond sensors spaced from one another. One of the second sensors 740may be coupled to the frame member 720 at or near the first set ofwheels 732, and the other second sensor 740 may be coupled to the framemember 720 at or near the second set of wheels 734. Similarly, the fifthsensor 746 may include two fifth sensors spaced from one another. One ofthe fifth sensors 746 may be coupled to the frame member 720 towards thefront end 712 and aligned with one of the second sensors 740, and theother of the fifth sensors 746 may be coupled to the frame member 720towards the front end 712 of the implement and aligned with the other ofthe second sensors 740. The third sensor 742 and the sixth sensor 748may each be coupled to the second frame section 706 at the front end 712and rear end 714, respectively.

Each of the plurality of sensors may be disposed in electricalcommunication with the ECU 212. The ECU 212 may include logic,algorithms, look-up tables, etc. for executing machine leveling controlmethods in accordance with this disclosure. Alternatively, thecontroller 206 of the work machine 200 may include logic, algorithms,etc. for executing the control methods. In any event, the plurality ofsensors shown in FIG. 7 may detect the distance from the frame to whichthe sensor is mounted and the ground, and communicate the detecteddistance to the ECU 212 or controller 206.

In one non-limiting example, the implement 700 may include a pluralityof work tools 726 for performing a work function. The plurality of worktools 726 may include rippers, disks, closers, etc. Each of theplurality of work tools 726 may be coupled to a frame member or asub-frame member, as will be described below. The plurality of worktools 726 may be coupled to the respective frame member at a defineddistance therefrom. Thus, if the work tool 726 is approximately twoinches below the frame member, and one of the sensors detects a distanceof four inches from ground, the ECU 212 or controller 206 may determinethat the work tool 726 is approximately two inches above the ground.This relationship between the work tool and frame member may be fixedsuch that the detected measurement by each sensor may be used forexecuting a machine leveling control process. This will be described infurther detail below.

With reference to FIG. 8 , an implement 800 is shown. The implement 800may include multiple sections, or it may only include a single section.In any event, the implement 800 may include a hitch assembly 806 coupledthereto at its front end 802 for coupling to a work machine (not shown).The implement 800 may include a main frame 808 that is coupled to thehitch assembly 806. The implement 800 may also include one or moresub-frames coupled thereto. In FIG. 8 , for example, a first sub-frame810 and a second sub-frame 812 are shown. Different work tools may becoupled to each sub-frame and the main frame 808. At least in thisembodiment, the first sub-frame 810 is disposed towards the front end802 of the implement 800, whereas the second sub-frame 812 is disposedtowards a rear end 804 thereof.

The frames may be supported by one or more wheels 820, 828. In thisembodiment, a front wheel 828 supports the implement 800 at its frontend 802, and a rear wheel 820 supports the rear end 804 of the implement800. Moreover, a first work tool 814 may be coupled to the firstsub-frame 810, a second work tool 816 may be coupled to the main frame808, and a third work tool 818 may be coupled to the second sub-frame812.

As also shown, a first sensor 822 is coupled to the first sub-frame 810and is configured to detect the distance between the first sub-frame 810and the underlying surface. Similarly, a second sensor 824 is coupled tothe main frame 808 and is configured to detect the distance between themain frame 808 and the underlying surface. Further, a third sensor 826is coupled to the second sub-frame 812 and is configured to detect thedistance between the second sub-frame 812 and the underlying surface. Insome instances, the sub-frames may be coupled to and below the mainframe. Thus, the distance between the first work tool 814 and theunderlying surface may be different than the distance between the secondwork tool 816 and the underlying surface. The same may be true withrespect to the third work tool 818. Since the distance between therespective frame and work tool may be predefined and stored within amemory unit of the ECU 212 or controller 206, the ECU 212 or controller206 may accurately detect the distance between the work tool and theunderlying surface to achieve uniform and desired tool depth.

In some cases, a drawbar height may be differ for different workmachines. This varying height can impact depth control. With the sensorslocated at each frame section and on main frames and sub-frames, thedepth of penetration of each work tool can be precisely controlled.Moreover, if a front wheel sinks into softer soil the implement 800 maybecome uneven in the fore-and-aft direction, i.e., the front end 802 ofthe implement 800 may be lower than the rear end 804. The first sensor822 may detect this change in distance between the first sub-frame 810and the ground and communicate the detected distance to the ECU 212 orcontroller 206. In turn, and to be described below, the ECU 212 orcontroller 206 may adjust the height of the first sub-frame 810 withrespect to the ground without requiring any user intervention. Similaradjustments can be made to the main frame 808 and second sub-frame 812as necessary. Thus, the implement 800 may be adjustably controlled tomaintain a level orientation with respect to the ground to ensure properwork tool depth during operation.

This is further shown in FIG. 9 . In this schematic, an implement 900 ormachine is shown positioned along an underlying surface or ground, G.While this embodiment refers specifically to an implement, a similarapplication may be made with respect to a machine. The implement 900 maytravel in a forward direction where its front end 902 faces the forwarddirection, and its rear end 904 is disposed at an opposite end. Theimplement 900 may include a front wheel 908 and a rear wheel 910 forsupporting a main frame 906. A front wheel arm 912 is coupled to thefront wheel 908 and pivotably coupled to the main frame 906 at a firstpivot location 916. Likewise, a rear wheel arm 914 is coupled to therear wheel 910 and pivotably coupled to the main frame 906 at a secondpivot location 918.

The implement 900 may further include a linkage 924 that is connected tothe front wheel arm 912 and rear wheel arm 914, as shown in FIG. 9 , toadjust the height of the front 902 of the implement 900 relative to therear 904. In many conventional applications, a turnbuckle is used formechanically adjusting the linkage in the fore and aft direction. Anactuator 920 may be coupled to the frame 906 and actuate in a directionindicated by arrow 922 to raise and lower the frame 906 relative to thefront and rear wheels. The turnbuckle, however, is actuated by a user oroperator via a wrench to mechanically adjust the linkage.

In the present disclosure, however, an actuator 926 is used to operablyadjust the linkage 924 without a user or operator having to make anymechanical adjustments. A controller such as the ECU 212 may be inelectrical communication with the actuator to extend or retract theactuator in a direction indicated by arrow 928 to adjust the linkage924. In an alternative embodiment, the actuator may be hydraulicallycontrolled to adjust the linkage 924. Thus, the rear actuator 920 mayautomatically adjust the height of the frame 906 with respect to theground, G, and the linkage actuator 926 may pitch the implement ormachine either forward or backward to achieve desirable machineleveling. In particular, the linkage actuator 926 may be actuated toadjust the length of the linkage and therefore adjust the height of thefront 902 of the implement 900. Moreover, with work tools being coupledto the main frame 906 of the implement 900, tool depth may be adjustedby extending or retracting either the linkage actuator 926 or the rearactuator 920 to achieve desired tool depth.

In the illustrated embodiment of FIG. 9 , the implement 900 may alsoinclude a first sensor 930 and a second sensor 932. The first sensor 930may be positioned towards the front of the machine near the front wheel908, and the second sensor 932 may be positioned towards the rear of themachine near the rear wheel 910. Each sensor may be in electricalcommunication with the ECU 212 or controller 206 and communicate adistance from the frame 906 to the ground, G. If the front wheel 908begins to sink in softer mud, the first sensor 930 may detect a shorterdistance from the front of the frame 906 to the ground compared to thedistance detected by the second sensor 932 of the rear of the frame 906to the ground. As such, the implement 900 may be pitched forward andthus uneven. The ECU 212 or controller 206 can operably control thelinkage actuator 926 according to any known means (e.g., electrically,hydraulically, etc.) to adjust the linkage 924 to achieve a levelorientation of the implement 900. For instance, the actuator 926 mayretract and thus shorten the linkage 924 to bring about the levelorientation.

In previous embodiments, tool depth is controlled via a series andparallel control system such as shown in FIGS. 1-6 . Here, Hall Effectsensors or the like may be positioned on or near the wheels to detectthe position of the wheel relative to the frame. The position of thewheel relative to the frame is used to infer or calculate the distanceof the tool from the ground. In some aspects, user input is used toestablish a distance or height of the tool from the ground. In theembodiments of FIGS. 7-10 , the same control system may be used toachieve implement or machine leveling. For example, the rear actuator920 in FIG. 9 may be hydraulically coupled to the control system 300 ofFIG. 3 . Here, fluid from the main pressure source 302 can flow throughthe first fluid path 308 into the second fluid path 310. The secondfluid path 310 is part of the parallel flow that may be used to controlboth tool depth and machine leveling across the width of the machine orimplement.

Referring, for example, to FIGS. 3, 7 and 10 , the height of each framesection 702, 704, 706 may be adjustably levelled by utilizing thesensors 738, 740, 742, 744, 746, and 748 coupled thereto. For example,if the first frame section 704 is detected by its sensors 738, 744 to be1.5 inches lower than the main frame section 702 and the second framesection 706, the ECU 212 or controller 206 may hydraulically controlfluid to flow through the second flow path 310 and to an actuator suchas the rear actuator 920 shown in FIG. 9 . A control valve similar tothe control valves 220, 224, 228, 232, and 236 shown in FIG. 10 may beelectrically controlled to its open position by the ECU 212 orcontroller 206 to allow fluid to flow therethrough and hydraulicallyactuate the actuator 920. As previously described, the rear actuator 920may be operably controlled to adjust the height of the frame relative tothe ground. As such, actuation of the rear actuator 920 of the firstframe section 704 can raise the frame 722 until it is level with themain frame section 702 and the first frame section 706.

In an embodiment similar to FIG. 1 where the implement includes morethan three frame sections, corrective action may be necessary in whichone of the inner frame section heights is adjusted. The correctiveaction, as described above, adjusts the outer frame section height afterthe inner frame section height is adjusted.

While FIGS. 3 and 10 illustrate a parallel-series control system, theimplement or machine may be levelled via a parallel-only control system.

Referring now to FIG. 10 , to level an individual frame section 1000 inthe fore and aft direction and maintain the front wheels and rear wheelson the same plane, a second control circuit 1004 may be provided. Here,a pressure line 1006 may be fluidly coupled between the pressure source302 and a second selective control valve 1002. The control valve 1002may be an electro-hydraulic valve that is actuated by the ECU 212 orcontroller 206. Alternatively, the valve may be a 3-position valve thatis biased in a normally closed position. A first pressure line 1010 anda second pressure 1012 may fluidly couple the valve 1002 to an actuator1008. For purposes of this embodiment, the actuator is a hydraulicactuator that may correspond with the linkage actuator 926 of FIG. 9 . Apiston may be hydraulically actuated in a direction indicated by arrow1014 to either extend or retract the linkage 924 and thus adjust thefront of the frame relative to the rear. Other types of valves andactuators may be used to control the orientation of the frame in thefore and aft direction.

As previously described, various types of sensors and sensingtechnologies may be used for machine or implement leveling. These mayinclude ultrasonic, optical, radar, and laser. Position sensors such aspotentiometers and hall effect sensors may be used. Alternatively, agyroscope or tilt sensor may be positioned on each frame section suchthat an angle of the section may be calculated with respect to othersections of the machine or implement. As such, the height of one sectionmay be determined based on the height of another. Other similartechnologies may be used for achieving a level machine or implementacross its width and from front-to-back.

While embodiments incorporating the principles of the present disclosurehave been described hereinabove, the present disclosure is not limitedto the described embodiments. Instead, this application is intended tocover any variations, uses, or adaptations of the disclosure using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains and which fallwithin the limits of the appended claims.

The invention claimed is:
 1. A work implement, comprising: atransversely extending frame including a front end and a rear end; ahitch member configured to couple to a work machine, the hitch memberbeing coupled to the front end of the frame; a front wheel and a rearwheel coupled to and supporting the frame, the front wheel and rearwheel adapted to move along an underlying surface; a front wheel armcoupled to the front wheel and pivotably coupled to the front end of theframe at a first pivot location; a rear wheel arm coupled to the rearwheel and pivotably coupled to the rear end of the frame at a secondpivot location; a linkage coupled to the front wheel arm and rear wheelarm, the linkage including a linkage actuator for adjustably controllinga length of the linkage; a first sensor coupled to the frame at or nearthe first pivot location, the first sensor configured to detect a firstheight of the frame relative to the underlying surface; a second sensorcoupled to the frame at or near the second pivot location, the secondsensor configured to detect a second height of the frame relative to theunderlying surface; and a control unit disposed in electricalcommunication with the first sensor and the second sensor, the controlunit operably controlling the linkage actuator based on the detectedfirst height and second height.
 2. The implement of claim 1, wherein thelinkage actuator comprises an electric actuator, hydraulic actuator, orelectro-hydraulic actuator.
 3. The implement of claim 1, wherein thecontrol unit compares the first height to the second height, and if thefirst height is not equal to or within a threshold limit of the secondheight, the linkage actuator is controllably actuated until the firstheight is equal to or within the threshold limit of the second height.4. The implement of claim 1, further comprising a second actuatorcoupled to the frame and the rear wheel arm, the second actuator beingactuated between a first position and a second position to raise orlower the frame relative to the underlying surface.
 5. The implement ofclaim 4, wherein the frame comprises a main frame and a sub-frame, themain frame including the first sensor and a first work tool, and thesub-frame including the second sensor and a second work tool; wherein,the linkage actuator is controllably actuated to maintain the main frameand sub-frame level with one another; and wherein, the second actuatoris controllably actuated to control a depth of the first work tool andsecond work tool relative to the underlying surface.
 6. The implement ofclaim 4, wherein the frame comprises a main frame, a first sub-frame,and a second sub-frame, the main frame including the first sensor and afirst work tool, the first sub-frame including the second sensor and asecond work tool, and the second sub-frame including a third sensor anda third work tool; wherein, the linkage actuator is controllablyactuated to maintain the main frame, the first sub-assembly and thesecond sub-assembly level with one another; and wherein, the secondactuator is controllably actuated to control a depth of the first worktool, the second work tool, and the third work tool relative to theunderlying surface.
 7. The implement of claim 4, further comprising: afirst fluid circuit fluidly coupled to a fluid source, the first fluidcircuit including a first control valve disposed in fluid communicationwith the linkage actuator, wherein the first control valve is operablycontrolled to actuate the linkage actuator between a retracted positionand an extended position; and a second fluid circuit coupled to thefluid source, the second fluid circuit including a second control valvedisposed in communication with the second actuator, wherein the secondcontrol valve is operably controlled to actuate the second actuatorbetween the first position and the second position.
 8. The implement ofclaim 1, wherein the frame comprises at least a first frame section, asecond frame section, and a third frame section, wherein the first framesection is disposed between the second and third frame sections; whereinthe implement further comprises a first actuator coupled to the firstframe section, a second actuator coupled to the second frame section,and a third actuator coupled to the third frame section; wherein thefirst and second sensors are coupled to the first frame section, thefirst sensor configured to detect a height of the front of the firstframe section relative to the underlying surface and the second sensorconfigured to detect a height of the rear of the first frame sectionrelative to the underlying surface; wherein the implement furthercomprises a third and a fourth sensor coupled to the second framesection, the third sensor configured to detect a height of the front ofthe second frame section relative to the underlying surface and thefourth sensor configured to detect a height of the rear of the secondframe section relative to the underlying surface; wherein the implementfurther comprises a fifth and a sixth sensor coupled to the third framesection, the fifth sensor configured to detect a height of the front ofthe third frame section relative to the underlying surface and the sixthsensor configured to detect a height of the rear of the third framesection relative to the underlying surface; and wherein the control unitcompares the heights detected by each sensor and adjustably controls thefirst actuator, the second actuator and the third actuator until eachheight is equal to or within a threshold limit of one another.
 9. Theimplement of claim 8, wherein each of the first frame section, thesecond frame section and the third frame section includes the linkageand linkage actuator; further wherein, the control unit operablycontrols the linkage actuator on each frame section so that the heightof the front of each frame section is equal to or within a thresholdlimit of the height of the rear of the respective frame section.
 10. Theimplement of claim 8, wherein each sensor comprises a tilt sensor fordetecting an angle of the respective frame section relative to the othertwo frame sections.
 11. The implement of claim 1, further comprising afluid circuit fluidly coupled to a fluid source, the fluid circuitincluding a control valve disposed in fluid communication with thelinkage actuator; wherein, the control valve is operably controlled toactuate the linkage actuator between a retracted position and anextended position.
 12. A work implement, comprising: a transverselyextending frame including a front end and a rear end; a hitch memberconfigured to couple to a work machine, the hitch member being coupledto the front end of the frame; a front wheel and a rear wheel coupled toand supporting the frame, the front wheel and rear wheel adapted to movealong an underlying surface; a front wheel arm coupled to the frontwheel and pivotably coupled to the front end of the frame at a firstpivot location; a rear wheel arm coupled to the rear wheel and pivotablycoupled to the rear end of the frame at a second pivot location; and arear actuator coupled to the frame and the rear wheel arm, the rearactuator being actuated between a first position and a second positionto raise or lower the frame relative to the underlying surface; whereinthe frame comprises a main frame, a first sub-frame, and a secondsub-frame, the main frame including a first work tool and a first sensorconfigured to detect a first height of the first work tool above orbelow the underlying surface, the first sub-frame including a secondwork tool and a second sensor configured to detect a second height ofthe second work tool above or below the underlying surface, and thesecond sub-frame including a third work tool and a third sensorconfigured to detect a third height of the third work tool above orbelow the underlying surface; and wherein the implement furthercomprises a control unit configured to controllably actuate the rearactuator based on the detected first, second, and third heights tocontrol a depth of the first work tool, the second work tool, and thethird work tool relative to the underlying surface.
 13. A workimplement, comprising: a hitch member configured to couple to a workmachine; a transversely extending frame being coupled to the hitchmember and including a first frame section, and a second frame section,wherein the first frame section includes: a first frame body havingfront end and a rear end, a front wheel and a rear wheel coupled to andsupporting the first frame body, the front wheel and rear wheel adaptedto move along an underlying surface, a front wheel arm coupled to thefront wheel and pivotably coupled to the front end of the first framebody at a first pivot location of the first frame section, a rear wheelarm coupled to the rear wheel and pivotably coupled to the rear end ofthe first frame body at a second pivot location of the first framesection, and a first rear actuator coupled to the first frame body andthe rear wheel arm, the first rear actuator being controllably actuatedbetween a first position and a second position to raise or lower thefirst frame section relative to the underlying surface, and wherein thesecond frame section includes: a second frame body having a front endand a rear end, a front wheel and a rear wheel coupled to and supportingthe second frame body, the front wheel and rear wheel adapted to movealong an underlying surface, a front wheel arm coupled to the frontwheel and pivotably coupled to the front end of the second frame body ata first pivot location of the second frame section, a rear wheel armcoupled to the rear wheel and pivotably coupled to the rear end of thesecond frame body at a second pivot location of the second framesection, a second rear actuator coupled to the second frame body and therear wheel arm, the second rear actuator being controllably actuatedbetween a first position and a second position to raise or lower thesecond frame section relative to the underlying surface independent ofthe first frame section.
 14. The work implement of claim 13 wherein:each of the first frame section and the second frame section includes alinkage coupled to the front wheel arm and the rear wheel arm of therespective frame section, a linkage actuator, and a control unit; andthe control unit operably controls the linkage actuator on each framesection to adjust the height of the front of each frame section to beequal to or within a threshold limit of the height of the rear of therespective frame section.
 15. The work implement of claim 13, furthercomprising: a first sensor coupled to the first frame section at or nearthe first pivot location of the first frame section, the first sensorconfigured to detect a first height of the first frame section relativeto the underlying surface; and a second sensor coupled to the firstframe section at or near the second pivot location of the first framesection, the second sensor configured to detect a second height of thefirst frame section relative to the underlying surface.
 16. The workimplement of claim 15, wherein: the first frame section includes a firstlinkage coupled to the front wheel arm and rear wheel arm of the firstframe section, the first linkage including a first linkage actuator foradjustably controlling a length of the first linkage; and the workimplement further comprises a control unit disposed in electricalcommunication with the first sensor and the second sensor, the controlunit operably controlling the linkage actuator based on the detectedfirst height and second height of the first frame section.
 17. The workimplement of claim 16, further comprising: a third sensor coupled to thesecond frame section at or near the first pivot location of the secondframe section, the third sensor configured to detect a first height ofthe second frame section relative to the underlying surface; and afourth sensor coupled to the second frame section at or near the secondpivot location of the second frame section, the second sensor configuredto detect a second height of the second frame section relative to theunderlying surface; wherein the second frame section includes a secondlinkage coupled to the front wheel arm and rear wheel arm of the secondframe section, the second linkage including a second linkage actuatorfor adjustably controlling a length of the second linkage; and whereinthe control unit is disposed in electrical communication with the thirdsensor and the fourth sensor, the control unit operably controlling thesecond linkage actuator based on the detected first height and secondheight of the second frame section.
 18. The work implement of claim 17,wherein the control unit compares the heights detected by each of thefirst, second, third, and fourth sensors and adjustably controls thefirst rear actuator and the second rear actuator until each height isequal to or within a threshold limit of one another.